Wordpress has has a security problem, any web visitor can easily know if your site is created with Worpdress by typing the URL to access the administration area (i.e. www.sitename.com/wp-admin). This allows hackers to hack the site easily once they crack the id and password.
The solution: the wSecure plugin. wSecure makes it so that “www.yoursite.com/wp-admin” will no longer bring up the admin page. Instead, wSecure allows you to set your own admin URL using a secret key (for example: www.yoursite.com/wp-admin/?secret). Only people who enter the secret key will be able to access your admin area.